1. Field of the Invention
The present invention relates to a lens barrel of a camera or the like and an imaging optical system provided with such lens barrel.
2. Background Art
Lens barrels, for example, of cameras are often provided with a position detection device for performing position control of a movable lens group. For example, when a movable lens group is moved with respect to a fixed tube by drive operating an annular lens engagement member that is engaged with the movable lens group, the lens drive position is detected by detecting the relative positions of the lens engagement member and the fixed tube. The technique for performing such position detection is disclosed, for example, in Japanese Patent Application Publication No. 2007-17679. An encoder device disclosed in Japanese Patent Application Publication No. 2007-17679 is provided with an electric section body in the form of a thin sheet and a plurality of sliding pieces having a sliding portion at the distal end and supported in the arranged state at the electric section body which constitutes an electric section (zoom brush). In the encoder device, the electric section body is screwed to an annular lens engagement member (zoom operation ring) and the movable lens group moves in the optical axis direction following the rotation of the lens engagement member. The sliding portion slides along the conductor pattern of the flexible printed board that is held at the fixed tube (fixed portion) and has the conductor pattern. Further, in the encoder device, the relative positions of the lens engagement member and the fixed tube are detected by detecting the combination of conductive states of the conductor pattern and the sliding portion.
However, in the encoder device described in Japanese Patent Application Publication No. 2007-17679, for example, when the thin-sheet electric section body is screwed to the lens engagement member, the electric section body is sometimes deflected in the arrangement direction of the sliding portions. Where such deformation occurs, the sliding portion can come into contact with the adjacent line of the conductor pattern when sliding along the conductor pattern.
Further, since the electric section is screwed to the lens engagement member, the lens engagement member is required to be thick enough so that the threaded hole for the screw could be formed therein and the space for arranging the screw is required. For this reason, the dimension of the lens engagement member in the diametrical direction increases and the lens engagement member is difficult to miniaturize. Furthermore, when the electric section is screwed to the lens engagement member, the position of the electric section with respect to the conductor pattern is difficult to adjust. For example, where the lens engagement member is displaced with respect to the fixed tube or an error has occurred in the production of the printed board, the electric section is difficult to set at the predetermined position with respect to the printed board.